Abrasive throwing machine



Sept. 15, 1942. I

A. BOESGER ABRASIVE THROWING MACHINE Filed Aug. 3, 1938 2 Sheets-Sheet 1 INVENTOR.

Z A Z r 1 0 p 15, G. A. BOESGER' I 2,295,926

ABRASIVE THROWINC; MACHINE 4 Filed Aug. 3, 1938 2 Sheets-Sheet 2 INVENTOR. 67 I 5 -6'e0/' 9e A. 309696 94 am ky ATTORNEYJ,

Patented Sept. 15, 1942 ABRASIVE THROWING MACHINE George A. Boesger, North olmste'd, Ohio, assignor to The W. W. Sly Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application August 3, 1938, Serial No. 222,888

6 Claims.

This invention relates to centrifugal throwing equipment for propelling abrasive grit and the like at a high velocity against objects to be cleaned and is more particularly concerned with cleaning equipment used in foundries for removing any molding sand which tends to cling to castings after they have been removed from the molds.

Abrasive throwing machines employing a rotating wheel with throwing surfaces thereon to centrifugally cast abrasive against the work are old. There has however, been considerable difficulty in feeding abrasive to the throwing surfaces of machines built prior to my invention.

Therefore, a primary object of the present invention has been toprovide a machine of novel construction of which an air-supply system is utilized to feed abrasive to the throwing blades and which overcomes the feeding difficulties heretofore encountered.

An additional object of my invention has been to invent apparatus of the class described in which I provide improved protection against wear due to the abrasive action, both as the same is thrown and as it rebounds from the work. Still another object has been to devise an equipment in which the parts susceptible to the most wear and subject to frequent replacement may be removed from the machine and new ones substituted therefor with a minimum of labor.

Other objects of the invention will become apparent from the following description when read in the light of the accompanying drawings, and

..: the novel features are summarized in the claims.

In said annexed drawings:

Fig. l is a side elevation partly in section of my improved blasting equipment;

Fig. 2 is a transverse section through Fig. l as indicated by the lines 22 thereon;

Figs. 3 and 4 are sections through Fig. 2 as shown by the lines 3-3 and 4-4 respectively; and

Fig. 5 is a detailed fragmentary section through Fig. 2, showing the blade construction and mounting.

In general my invention is adapted to be mounted on flooring situated at two levels. The lower level supports a base which in'turnflcarries a driving motor connected to the impeller wheel, which is preferably mounted on the easing of the blasting chamber and discharges through an opening therein against the work to be cleaned. Supported by flooring above the impeller wheel is a blower connected by suitable piping to discharge a column of air adjacent the heels of the impeller blades. An abrasive hopper discharges downwardly in the path of the air column. The abrasive is discharged through an enlarged Pitot tube into the air column and thus the abrasive is blown into the path of the blades and discharged thereby against the work. I provide a Venturi nozzle to guide the air column at the point where the abrasive is discharged therein and find that this increases the rate of feeding and aids in drawing theabrasive'into the air column. Adjustments, as hereafter described, are provided to control the angle of blast through an arc of approximately Referring to Fig. l, I provide a motor stand [0 carried by the flooring l2, in which is mounted a power control cabinet for the driving motors of the equipment. The upper portion of the stand is provided with an angular face I4 disposed as shown in Fig. 1. This angle-is determined by the angle of discharge at which it is desired to project the abrasive blast against the work. As shown in Fig. l, the equipment is mounted to project such blast at an angle normal to the face I 4 and on the opposite side of the impeller from that there seen.

A driving motor to rotate the impeller wheel is bolted to the face l4 and is of the enclosed fan-cooled type, driving the impeller shaft designated at l5 through several strands of V-belting 11 passing over a motor sheave l8 and a shaft sheave H].

The impeller shaft is journalled in roller thrust bearings carried by pillow blocks 2| and sealed against the ingress of abrasive dust in the surrounding atmosphere. The pillow blocks are mounted on a steel base 22 which is bolted as at 24 to the side of the abrasive blast chamber. The impeller case, designated generally at 25, is also bolted to the walls defining the abrasive chamber, as best shown in Fig. 2. As there shown, the casing comprises a casting 30 fitting over the abrasive discharge opening 32 formed in the walls of the blast chamber 34 and suitably bolted thereto as at 35.

A sheet steel casing proper is pivotally mounted on the casting 30 at 3| and at the other side is held down on the casting by a hook 32 which is adjustable and pivotally carried by the casting at 33. This sheet steel casing comprises a pair of sides 35 and 36 to which is welded an annular outer shell 38 conforming to the'periphery of the impeller. opening 31 for the impeller shaft [5' and the side 36 is recessed at 39 to provide an opening The side 35 is provided with an 7 to receive the abrasive feed pipe as hereafter described.

A discharge pipe leading to the impeller and indicated at 40 is bolted at 43 to a plate 45. The plate is pivotally mounted on a bolt 46 threadingly received in a boss 48 of the casting 39 such that the bolt axis and shaft axis are in line. The plate 45 (Fig. 4) is slotted as at 49 to accommodate a bolt 50 which in turn is threadingly secured in the side 36 to lock the discharge pipe in any adjusted position. A retainer plate. indicated at 52, through which the bolt 46 passes, is utilized to axially retain the plate 45 in position at its lower portion.

With many impeller wheels of the type generally known, abrasive is discharged from a cen-- tral stationary feeding cage opening outwardly into the path of the rotating blades. The result is a marked wiping effect of the abrasive against the outer portion of the cage as the abrasive is pushed thereover by the blades. This results in very rapid wear of the cage and the heels of the impeller blades, thus requiring frequent replacement. Furthermore, a positive feeding means in the form of a small impeller within the large impeller is employed in these machines to move the abrasive mass into position to be picked up by the throwing blades. Here again wear is a very important factor, as well as necessitating additional moving parts.

With my improved impeller wheel the blades extend inwardly until adjacent blades are in contact at the axis and abrasive is fed thereto from the nozzle 49 spaced axially thereof. The air column used for feeding abrasive into the heel of the blades of my improved machine results in a much improved patternwithout the wear or any necessity for the additional moving parts of prior construction.

Adjustment of the discharging position of the feed pipe 49, necessary to control the angle of blast from the wheel, is obtained by loosening the bolt 50 and shifting the plate 45 about its pivoted mounting on the bolt 46. Thus, as shown in Fig. 4, the discharge of the feed pipe may be varied through an arc of approximately 120 and may, for example, occupy, in addition to the solid line showing, a position indicated in the dotted lines on that figure. To permit setting of the discharge at any convenient point, a scale plate 55 is mounted on the plate 36 and a corresponding pointer finger is carried by the plate 45.

Abrasive is supplied to the discharge pipe 40 by means of an abrasive hopper and a motordriven blower. Referring again to Fig. 1, the hopper comprises a funnel which forms the lower portion of a storage hopper for cleaned abrasive. The hopper discharges through'a nozzle 58 into a second funnel 60 and by reason of the air space surrounding the nozzle 58, which is open to the atmosphere, there is no formation of vacuum in the feed line. As abrasive passes through the funnel 69 it is guided by a curved pipe 62 into a removable hardened steel sleeve 64 from whence it is discharged into the air passage.

Air for feeding abrasive is blown past the outlet of the sleeve 64 through a Venturi nozzle formed in the injection chamber to combine with the Pitot tube action of sleeve 64. Air is supplied by a blower 65 driven by an electric motor direct coupled thereto. A flexible connection 63 connects the blower with the injection chamber to permit adjustment of the parts.

As air is blown through the injection chamber and past the discharge of the sleeve 64 it increases in velocity by reason of the Venturi action and picks up abrasive fed through the sleeve and blows the same against the heel portion of the impeller wheel, from whence it is then picked up and centrifugally cast by the wheel blades.

The impeller wheel proper is best shown in Figs. 2 and 3 and is mounted for rotation on the shaft [5. The wheel comprises a disk 15 terminating in a collar il fixedly secured to a sleeve 18 by suitable screws 19. The sleeve in turn is mounted for rotation with the shaft.

Carried by the disk are four impeller blades spaced apart and each extending inwardly to overlie the end of the shaft and to contact each other adjacent the disk axis. Each blade, designated at 89. is shaped as shown in crosssection in Fig. 5 and includes a pair of locking flanges 82 and 84 which coact to form with the blade edge a roughly triangular projection. These portions of the blades are angularly engaged by overlying retaining plates 86. The flat edge of each blade is provided with four transverse ribs 81 each adapted to be in a corresponding slot of the disk 15. The blades extend outwardly and the abrasive carrying face is slightly concaved to place the unsupported edge slightly above the supported edge, as shown in Fig. 5. The unsupported edge terminates in an upstanding lip 88 by which abrasive is prevented from sidewise discharge from the machine. A cooperating lip 89 is provided as shown in this figure to form, with lip 88, an abrasive path to carry the same to the outer periphery of the wheel.

The blades are retained in position against the disk 15 by the aforementioned retainer plates 86 acting to hold ribs 81 in the cooperating slots of the disk 15. The retainer plates are bolted as at 9| to the disk 15, and by drawing the bolts tightly the ribs are supported in the disk slots and the blades are secured in outwardly extending position to receive and throw abrasive. As the bolts 9| are loosened the blades free themselves from the slots and move outwardly under the impetus of leaf springs 93 interposed between disk 15 and respective blades (Figs. 2 and 5). This makes for easy blade replacement. Referring to Figs. 2 and 3, it will be seen that the lip portion 88 inwardly terminates at 92 to prevent interference of the p with the abrasive fed through the discharge pipe 40.

In operation the apparatus described functions as follows. A supply of abrasive drops by gravity from the hopper 51 into the feed pipe 62 and sleeve 64, and from whence it discharges to the Venturi nozzle of the injection chamber 10. At this time the column of air created by the fan 65 blows the abrasive into position to be picked up by the impeller blades 80. The discharge point of the pipe 49, as indicated best in Fig. 4, is closely adjacent the axis of the rotating impeller and the abrasive is picked up by the throwing faces of the blades and, due to the high rotative speed thereof, is discharged centrifugally with great force against the articles to be cleaned.

The adjustment by which .the discharge point of the pipe 40 is controlled is adapted to permit circumferentially shifting the pipes through an angle of approximately It is a characteristic of my machine that abrasive fed thereto is discharged roughly from the feeding position and it is thus possible to closely control the discharge pattern by the adjusted position of the abrasive feed pipe.

Throughout my specification I have referred to the invention as "handling abrasive, and by this is meant sand or crushed steel grit and the like, such as is used for cleaning castings and similar articles due to the abrasive action therewith.

The wear of the abrasive traveling at high speeds on the parts of the equipment with which it comes in contact is-enormous. A feature of my invention, as elsewhere indicated, is to incorporate a design eliminating as much' as possible the excess wear occasioned by rapidly traveling abrasive over the parts. It has also been a feature of my invention to permit ready replacement of those parts which wear rapidly and which particularly include the blades and the feeding means closely allied therewith. Other portions of the equipment may be protected to decrease the wear and these protecting elements are also subject to frequent replacement and have .been worked out with that in view.

Thus the steel sleeve 64, the Venturi nozzle section indicated at 12, the injection nozzle or feed pipe 40, as well as the various parts of the impeller contacted by the abrasive, are all subject to replacement, although some parts wear out much more rapidly than others. The two parts most frequently replaced are the injection nozzle 40 and the blades 80. In order'to decrease wear on these parts as much as possible they should be made of hard ferrous metal or veryhard alloys which are highly resistant to abrasion. In any event, .the blades wear so rapidly that they must be replaced very often and in many cases as frequently as once a day.

Not all of the abrasive thrown by the impeller or wheel is discharged against the work. There is a small fraction discharged from the wheel at all points about the periphery thereof and, to protect the case, a removable guard member is provided to line the same. This member, indicated at 95, is best shown in Figs. 2 and 3 and comprises an annular ring extending completely around the impeller and conforming in contour therewith. The ring is made in two parts, 96 and 91, carried by the case and the casting 30 respectively. The part 98 extends the entire width of the case and is removably fastened thereto by bolts 99 and is spaced from the case by rings I interposed between the parts. The lower segment 9! is fastened to the angle member NH and this in turn is bolted to the downwardly extending skirt I03 of the casting 30. The segment 91 extends outwardly unsupported from the angle l0! far enough to prevent rebounding abrasive from reaching the shaft l and not far enough to interfere with the pattern of abrasive discharged from the impeller.

Abrasive is discharged from the impeller, as above stated, in a definite pattern determined by an angular location of the discharge pipe 49. This pattern, which may be roughly varied through 120 of arc, tends to be ineffective at its outer edges parallel to the impeller axis because there a relatively small amount of abrasive contacts the work. This limitation is inherent in any blasting machine throwing a pattern, and because the tumbling equipment must be strong enough to support very heavy loads of castings the surface extent of the material to be cleaned is limited to the effective pattern of the machine. As a result a portion of the tumbling equipment is normally exposed to the action of stray abrasive, which results in rapid wear of the parts'and frequent replacement of the exposedportions of the equipment. To obviate this difficulty I have provided adjustable baflle plates by which the outer extremities of the pattern parallel to the axis are definitely controlled and thus I direct the entire effective abrasive charge onto the work, at the same time protecting the tumbling equipment from the blast.

These baflles are indicated at H15 and [0! in Fig. 4 and are pivotally mounted to permit their adjustment as the angle of blast is varied. Each baffle comprises a plate extending below the outer periphery of the impeller and terminating at its other end in a flange portion perpendicular to the impeller axis. The fiange portion of each baffle is secured as by welding to a plate l II], which is roughly triangular in cross-section, as indicated in Fig. 4, and is pivotally mounted on an inwardly extending boss of the shoulder 48 of the casing 30. To lock the plate H0 and the baffle supported thereby in any adjusted position an angle plate H2 is provided secured to the under side of the casing 34 by bolts 3. The angle member is drilled to accommodate a bolt H4 surmounted by a nut H5 and which slidingly occupies a slot in the plate I Hi. This slot is roughly in length (corresponding to the variation in the angle of discharge desired) and lies in the radius about which the plate I l 0 is free to swing. Thus the baffles may be located in any adjusted position and securely held there by tightening the clamping nut H5 on this bolt. To reduce wear on the baffles the same are preferably coated with a rubber wear plate on the abrasive adjacent side, since the rubber when subjected to the abrasive blast wears much less rapidly than does the steel plates from which the baffles are formed.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In an abrasive throwing machine, a shaft mounted for rotation, a disk with a flat radial face mounted on said shaft, a plurality of abrasive throwing blades adapted to be mounted on said disk each comprising a relatively flat portion adapted to receive and propel abrasive, an upturned lip at one edge of said propelling face extending from the outer end-to but not beyond substantially the mid-point of the blade length, said lip being substantially parallel with the rad al face of the disk, means to mount said blades on said disk and an abrasive discharge feed pipe mounted to discharge beyond the outer radial edge of said blades and within a circle formed by the inner rotating edges of said lips closely adjacent to the disk axis of rotation and directly from said discharge feed pipe onto said blades.

2. In a machine of the character described a rotary impeller mounted for rotation about an inclined axis, said impeller carrying a plurality of blades thereon intersecting at the axis of rotation to form a plurality of abrasive receiving pockets, said blades bounding the pockets and providing throwing faces of a length substantially equal to the radius of the impeller, and an abrasive discharge tube in axial alignment with the axis of the impeller and discharging abrasive into the bottom of said pockets.

3. In a machine of the character described a rotary driveshaft inclined-with respect to the horizontaland-carrying adisk thereon having a radial face inclined in the opposite direction, bladeson said radial face intersecting at the axis-of the disk to form inclined pockets bounded by'substantially-radial throwing faces, and means to'feed abrasive to thepockets adjacent the axis of the disk but above a horizontal line extending therethrough. I

luIn'an abrasive throwing machine, a shaft xmounted'for rotation, a disk with a flatradial face mounted on said shaft, a plurality of abrasive throwing blades adapted to be mounted on said disk, each comprising a relatively flat portion adapted to receive and propel abrasive, an

upturned lip at one edge of said propelling face extending fromthe outer end to but not beyond substantially'the mid-point of the blade length, said lip being substantially parallel with the radial face 'of the disk,'a plurality of retaining plates secured-to said disk to hold said blades in position on said disk, and an abrasive discharge feed pipe-mounted to discharge beyond the outer radial edge of said'blades and within a circle formed by the inner rotating edges of said lips closely adjacent to the disk'axis of rotation and directly from said discharge feed pipe onto said blades.

5. In an abrasive throwing machine, a shaft mounted for rotation, a disk with a flat radial face mounted'on said shaft, a plurality of abrasive throwing blades adapted to be mounted on saidvdisk, each comprising a relatively flat portion adaptedto receive and propel abrasive, an upturned lipat one edge of said propelling face extending from the outer end to but not beyond substantially the mid-point of the bladelength, said lip being substantially parallel with the radial face of the disk, shouldersformed in said disk and engaging with shoulders formed'on said blades, respectively, to limit the outward radial movement of aid blades with respect to said disk, and an abrasive discharge feed pipe mounted-to discharge beyond the outer radial edge ofsaid blades and within a circle formed by the'inner rotating edges of said lips closely adjacent to the disk axis of rotation and directly'from sai discharge feed pipe onto said blades. 1

6. In an abrasive throwing machine, a shaft mounted for rotation, a disk with a flat radial face mounted on said shaft, a plurality of abrasive throwing blades adapted to be mounted on said disk, each comprising a relatively flat portion adapted to receive and propel abrasive, an upturned lip atone edge of said propelling face extending from the outer end to but not beyond substantially the mid-point of the blade length, said lip being substantially parallel with the radial face of the disk, a plurality of retaining plates-secured to said disk to hold said blades in position on said disk, shoulders formed in said disk engaging with shoulders formed 'on said blades, respectively, to limit the outward radial movement of said blades with respect to said disk, and an abrasive discharge feedpipe mounted to discharge beyond the outer radial edge of said blades and within a circle formed by the inner rotating edges of said lips closely adjacent to the disk axis of rotation and directly from said discharge feed pipe onto-said blades.

GEORGE A. BOESGER. 

